This invention relates in general to material excavation method and apparatus, and in particular relates to method and apparatus for the excavation and removal of a settled body of discrete mineral solids such as a tailings pond from an ore mining operation or any other settled body of material which may be constrained by any means such as a large container or vessel and the like.
The mineral or ore solids which are normally discharged as waste products from mining operations and the like must be disposed of in a suitable manner. It is present practice in a mining operation to deposit the tailings or waste mineral solids from operations such as ore dressing into a tailings pond which may be a dammed up area near the mining operation. The tailings pond contains the tailings in a substantially homogeneous mass of water and mineral solids. After a period of time, this mass settles into a semi-rigid body of discrete mineral solids as a certain percentage of the water is expelled.
For various reasons including the fact that tailings ponds of the above nature contain minerals of sufficient value to justify economic recovery, or exist above unmined ore bodies that cannot be mined with the tailings pond in place, or are so located as to endanger entire communities should the associated retaining dam break loose and the tailings ponds begin to flow, it is desirable to excavate, remove, and transport away the mineral solids from the pond. Present techniques such as clam shelling or dredging are limited in their ability to do this work. In the above-identified patents, in particular U.S. Pat. No. 3,606,479, there are disclosed methods and apparatus for the handling of particulate material in which a settled body of the material is removed by the action of fluid jets mounted for operation in the lower-most region of the containing vessel, such as a ship's hold. However, these methods and apparatus are not applicable to excavation operations which can be carried out from the surface of the settled body and progress downwardly in stages to the required depth. Accordingly, the need has been recognized for improved method and apparatus which is effective in excavating and removing a settled body of mineral solids of the above nature.